Method and apparatus for in-device coexistence (IDC) indication

ABSTRACT

This disclosure relates to methods and apparatuses for In-Device Coexistence (IDC) indication. Among other things, the present disclosure presents a method performed by a user equipment (UE). The UE is configured to send  201  an IDC indication message with a same content as in a previously sent IDC indication message if, or when, the UE has performed a handover to another cell (target cell).

PRIORITY

This application is a continuation, under 35 U.S.C. § 120, of U.S.application Ser. No. 14/996,765 filed Jun. 21, 2013, which is a nationalstage filing under 35 U.S.C. § 371 of International Patent ApplicationSerial No. PCT/SE2013/050469 filed Apr. 26, 2013, and entitled “METHODAND APPARATUS FOR IN-DEVICE COEXISTENCE (IDC) INDICATION” which claimspriority to U.S. Provisional Patent Application No. 61/707,206 filedSep. 28, 2012, both of which are hereby incorporated by reference intheir entirety.

TECHNICAL FIELD

The technology described in this disclosure relates to cellular radiocommunications and finds one non-limiting example to an EvolvedUniversal Terrestrial Radio Access Network (E-UTRAN). More particularly,the present disclosure presents methods and apparatuses for In-DeviceCoexistence (IDC) indication.

BACKGROUND

This section is intended to provide a background to the variousembodiments of the invention that are described in this disclosure. Thedescription herein may include concepts that could be pursued, but arenot necessarily ones that have been previously conceived or pursued.Therefore, unless otherwise indicated herein, what is described in thissection is not prior art to the description and/or claims of thisdisclosure and is not admitted to be prior art by the mere inclusion inthis section.

FIG. 1 is an illustration of an example EUTRAN which is the airinterface of the 3^(rd) Generation Partnership Project's (3GPP) LongTerm Evolution (LTE) of mobile communication networks. As is known amongpersons skilled in the art, the LTE radio access network uses a flatarchitecture with a single type of node, i.e. the evolved NodeB (eNB).The eNB is generally responsible for radio-related functions in one orseveral radio cells. As can be seen in FIG. 1, the eNB's are connectedto the Evolved Packet Core (EPC) by means of the S1 interface. Moreparticularly, the eNB's can be connected to a Serving Gateway (S-GW) bymeans of a S1 user-plane part, S1-u. Also, the eNB's can be connected toa Management Mobility Entity (MME) by means of a S1 control-plane part,S1-c. Furthermore, a Packet Data Network Gateway (PDN Gateway, P-GW) mayconnect the EPC to the Internet. Moreover, the X2 interface is theinterface that connects the eNB's to each other. A more detaileddescription of the radio-interface architecture can be found inliterature, such as in the reference book 4G LTE/LTE-Advanced for MobileBroadband by Erik Dahlman, Stefan Parkvall and Johan Sköld, AcademicPress, 2011, ISBN:978-0-12-385489-6, see e.g. chapter 8 “Radio-InterfaceArchitecture”.

More mobile devices, smartphones, etc. are and will be equipped withmultiple radio transceivers in order to access various networks. Forexample, a User Equipment (UE) may be equipped with LTE, WiFi, andBluetooth transceivers, and Global Navigation Satellites Systems (GNSS)receivers. When the radio transceivers within the same UE, which areclose to each other, operate on adjacent frequencies or sub-harmonicfrequencies, transmissions associated with one radio transmitter mayinterfere with the receiver of another radio. This interferencesituation is referred to as an In-Device Coexistence (IDC) interferencescenario, or IDC interference situation.

One approach to address this IDC interference problem, or IDCinterference situation, is to minimize IDC interference betweenco-located radio transceivers by filtering. However, this may betechnically challenging and expensive such that alternative solutionsare needed. Another approach is to essentially move the interferingsignal or signals either in frequency domain or in the time domain sothat interference is reduced between the radios.

Currently, the 3GPP is standardizing signaling mechanisms for in-devicecoexistence (IDC) interference avoidance. The current status of thesolution is described in a Change Request (CR) R2-124311 for the 3GPPTechnical Specification TS 36.300. The R2-124311 was presented at a 3GPPmeeting in Qingdao, China, Aug. 13-17, 2012. The contents of R2-124311can be found in Appendix A (see also,ftp://ftp.3gpp.org/tsg_ran/WG2_RL2/TSGR2_79/Docs/R2-124311 zip)

In support of the IDC interference avoidance is the signaling between aUE and the network, e.g., a base station such as an eNB. A UE thatsupports IDC functionality indicates this capability to the network, andthe network can then configure by dedicated signaling whether the UE isallowed to send an IDC indication. The UE may only send an IDCindication for E-UTRA uplink/downlink (UL/DL) carriers for which aMeasurement Object (MO) is configured. When a UE experiences a level ofIDC interference that cannot be solved by the UE itself and a networkintervention is required, the UE sends an “IDC indication” via dedicatedRRC (Radio Resource Control) signaling to report the IDC interferenceproblem. The IDC indication is preferably triggered based on actualongoing IDC interference on the serving and/or non-serving frequenciesrather than on assumptions or predictions of potential interference.When notified of an IDC problem via IDC indication signaling from theUE, the eNB may apply, for example, a Frequency Division Multiplexing(FDM) solution or a Time Division Multiplexing (TDM) solution.

An example of an FDM solution is moving an LTE signal further away fromthe industrial, scientific and medical (ISM) band by performinginter-frequency handover within E-UTRAN to WCDMA or other similartechnologies. An example of a TDM solution is to ensure thattransmission of a radio signal does not coincide with reception ofanother radio signal during the same time slot or period. The LTEDiscontinuous Reception (DRX) mechanism may be used to provide TDMpatterns (i.e., periods during which the UE's LTE transceiver may bescheduled or not scheduled) to resolve IDC issues. A DRX-based TDMsolution is preferably used in a predictable way, e.g., the eNB ensuresa predictable pattern of unscheduled periods using a DRX type mechanism.

To assist the eNB in selecting an appropriate solution, IDC assistanceinformation for both FDM and TDM solutions may be sent by the UEtogether with the IDC indication to the eNB. The IDC assistanceinformation comprises, for example, a list of E-UTRA carriers sufferingfrom ongoing interference, the direction of the interference, TDMpatterns or parameters to enable appropriate DRX configuration for TDMsolutions on the serving E-UTRA carrier, and/or an indication ifinterference is over. In case of an inter-eNB handover, the IDCassistance information is preferably transferred from the source eNB tothe target eNB.

A prohibit mechanism, such as an IDC indication prohibit timer, may beused to restrict the time interval at which the UE sends an IDCindication in order to avoid unnecessary IDC indication signaling. Forexample, a prohibit timer can prohibit the UE from sending another IDCindication message soon after it previously sent an earlier IDCindication message. When the UE sends an IDC indication, the UE maystart an IDC indication prohibit timer. The UE is generally not allowedto send a new IDC indication as long as prohibit timer is running.Alternatively, an IDC indication prohibit timer may be applicable to allnew IDC indication messages. In this alternative, the UE may be furtherrestricted to not send the same IDC indication content to the network asthe UE sent earlier—irrespective of the status of the prohibit timer.Another alternative applies an IDC indication prohibit timer only to anIDC indication message whose content has changed from the previouslysent IDC indication message.

A problem with these approaches is that an IDC indication cannot be sentby the UE even if it is actually needed, e.g. needed by the network.Although an IDC indication prohibit timer could be configured to a smallvalue timeout to ameliorate this situation, a too short an IDCindication prohibit timer value can lead to a heavy signaling loadconsuming valuable radio resources as well as an increased computationalload in network nodes.

SUMMARY

It is in view of the above considerations and others that the variousembodiments of the present invention have been made.

In one non-limiting example embodiment, a UE sends an IDC indicationmessage irrespective of an IDC indication prohibit timer when time-basedparameters, e.g., time division multiplex (TDM) parameters, change inthe IDC indication message. In another non-limiting example embodiment,a UE is not permitted to send an IDC indication message where the samecontent in the IDC indication has not changed from the previously sentIDC indication message—irrespective of the UE's IDC indication prohibittimer. In yet another example embodiment, the UE is allowed to resendthe same IDC indication after a handover—irrespective of the UE's IDCindication prohibit timer—to ensure that the target eNB receives thecorrect IDC information.

More particularly and according to a first aspect, there is provided amethod performed by a user equipment (UE). The method comprises sendingan In-Device Coexistence (IDC) indication message with a same content asin a previously sent IDC indication message if the UE has performed ahandover to another cell (which may hereinafter also be referred to as“target cell”). In other words, the method may comprise sending an IDCindication message which is the same as the previously sent IDCindication message if, or when, the UE has performed a handover toanother radio cell. As will be appreciated, the above-mentionedpreviously sent IDC indication message was sent by the same UE.

In one embodiment, the method may comprise sending, in a target cell,the IDC indication message with the same content as in the previouslysent IDC indication message if the UE has sent the IDC indicationmessage to a source evolved NodeB (eNB) later than a previousmeasurement report has been sent. In other words, the method maycomprise sending, in a target cell, the IDC indication message with thesame content as in the previously sent IDC indication message if the UEhas sent the IDC indication message to a source evolved NodeB (eNB)later than the same UE has sent a previous measurement report to thesame source eNB.

In one embodiment, the method may comprise sending, in a target cell,the IDC indication message with a same comment as in the previously sentIDC indication message if the UE has sent the IDC indication message toa source eNB a maximum number of seconds before the UE has received ahandover command. The maximum number of seconds may be a fixed time.Alternatively, the maximum number of seconds may be a configurable time.The maximum number of seconds may, for example, be 0.5, 0.75, 1, 1.25,1.5, or 2 seconds.

It should be appreciated that the IDC indication message (which is sentwith the same content as in a previously sent IDC indication message ifthe UE has performed a handover to another cell) may be sent to a targeteNB.

According to a second aspect, there is provided a user equipment (UE).The UE comprises a controller with one or more data processors and oneor more memories connected to the one or more data processors. The oneor more memories store program and other information and data which,when, run in the one or more data processors causes the UE to send anIn-Device Coexistence (IDC) indication message with a same content as ina previously sent IDC indication message if the UE has performed ahandover to another cell.

In one embodiment, the one or more memories store program and otherinformation and data which, when, run in the one or more data processorscauses the UE to send, in a target cell, the IDC indication message withthe same content as in the previously sent IDC indication message if theUE has sent the IDC indication message to a source evolved NodeB (eNB)later than a previous measurement report has been sent.

In one embodiment, the one or more memories store program and otherinformation and data which, when, run in the one or more data processorscauses the UE to send, in a target cell, the IDC indication message witha same comment as in the previously sent IDC indication message if theUE has sent the IDC indication message to a source eNB a maximum numberof seconds before the UE has received a handover command. The maximumnumber of seconds may be a fixed time. Alternatively, the maximum numberof seconds may be a configurable time. The maximum number of secondsmay, for example, be 0.5, 0.75, 1, 1.25, 1.5, or 2 seconds.

In one embodiment, the one or more memories store program and otherinformation and data which, when, run in the one or more data processorscauses the UE to send the IDC indication message with the same contentas in the previously sent IDC indication message to a target eNB.

According to a third aspect, there is provided a method performed by auser equipment (UE). The method comprises transmitting an In-DeviceCoexistence (IDC) indication message to a network after a time parameteror a frequency parameter changes.

In one embodiment, the method may comprise sending the IDC indicationmessage to a base station (e.g. a eNB).

In one embodiment, the time parameter is a Time Division Multiplexing(TDM) parameter.

In one embodiment, the frequency parameter is a Frequency DivisionMultiplexing (FDM) parameter.

In one embodiment, the method may comprise resending the IDC indicationmessage irrespective of an IDC indication prohibit timer. For example,the method may comprise resending the IDC indication messageirrespective of an IDC indication prohibit timer if one or more timeparameters (e.g. TDM parameters) have changed but not when frequencyparameters (e.g. FDM parameters) have changed. Alternatively, the methodmay comprise resending the IDC indication message irrespective of an IDCindication prohibit timer if one or more frequency parameters (e.g. FDMparameters) have changed but not when time parameters (e.g. TDMparameters) have changed.

According to a fourth aspect, there is provided a user equipment (UE).This UE comprises a controller with one or more data processors and oneor more memories connected to the one or more data processors; whereinthe one or more memories store program and other information and datawhich, when, run in the one or more data processors causes the UE totransmit an In-Device Coexistence, IDC, indication message to a network(e.g. a base station) after a time parameter or a frequency parameterchanges.

In one embodiment, the time parameter is a Time Division Multiplexing(TDM) parameter.

In one embodiment, the frequency parameter is a Frequency DivisionMultiplexing (FDM) parameter.

In one embodiment, the one or more memories may store program and otherinformation and data which, when, run in the one or more data processorscauses the UE to resend the IDC indication message irrespective of anIDC indication prohibit timer. For example, the one or more memories maystore program and other information and data which, when, run in the oneor more data processors causes the UE to resend the IDC indicationmessage irrespective of an IDC indication prohibit timer if one or moretime parameters (e.g. TDM parameters) have changed but not whenfrequency parameters (e.g. FDM parameters) have changed. Alternatively,the one or more memories may store program and other information anddata which, when, run in the one or more data processors causes the UEto resend the IDC indication message irrespective of an IDC indicationprohibit timer if one or more frequency parameters (e.g. FDM parameters)have changed but not when time parameters (e.g. TDM parameters) havechanged.

BRIEF DESCRIPTION OF THE DRAWINGS

These and other aspects, features and advantages of the invention willbe apparent and elucidated from the following description of embodimentsof the present invention, reference being made to the accompanyingdrawings, in which:

FIG. 1 shows an illustration of an example EUTRAN;

FIG. 2 shows a simplified signaling diagram illustrating an exampleembodiment where a UE is allowed to send an IDC indication with the samecontent as in the previous IDC indication message if it has performedhandover to another cell;

FIG. 3 shows a signaling diagram illustrating an example embodimentwhere a UE sends an IDC indication with the same content as in aprevious message in a target cell (e.g. target eNB) if it has sent theprevious IDC indication to the source eNB later than a previousmeasurement report was sent to the source eNB;

FIG. 4 shows an example embodiment of a base station, e.g. an eNB; and

FIG. 5 shows an example embodiment of a user equipment.

DETAILED DESCRIPTION

The following sets forth specific details, such as particularembodiments for purposes of explanation and not limitation. It will beappreciated by one skilled in the art that other embodiments may beemployed apart from these specific details. In some instances, detaileddescriptions of well known methods, nodes, interfaces, circuits, anddevices are omitted so as not obscure the description with unnecessarydetail. Those skilled in the art will appreciate that the functionsdescribed may be implemented in one or more nodes using hardwarecircuitry (e.g., analog and/or discrete logic gates interconnected toperform a specialized function, ASICs, PLAs, etc.) and/or using softwareprograms and data in conjunction with one or more digitalmicroprocessors or general purpose computers. Nodes that communicateusing the air interface also have suitable radio communicationscircuitry. Moreover, the technology can additionally be considered to beembodied entirely within any form of computer-readable memory, such assolid-state memory, magnetic disk, or optical disk containing anappropriate set of computer instructions that would cause a processor tocarry out the techniques described herein.

Hardware implementation may include or encompass, without limitation,digital signal processor (DSP) hardware, a reduced instruction setprocessor, hardware (e.g., digital or analog) circuitry including butnot limited to application specific integrated circuit(s) (ASIC) and/orfield programmable gate array(s) (FPGA(s)), and (where appropriate)state machines capable of performing such functions.

In terms of computer implementation, a computer is generally understoodto comprise one or more processors or one or more controllers, and theterms computer, processor, and controller may be employedinterchangeably. When provided by a computer, processor, or controller,the functions may be provided by a single dedicated computer orprocessor or controller, by a single shared computer or processor orcontroller, or by a plurality of individual computers or processors orcontrollers, some of which may be shared or distributed. Moreover, theterm “processor” or “controller” also refers to other hardware capableof performing such functions and/or executing software, such as theexample hardware recited above.

It should be understood by the skilled in the art that “UE” is anon-limiting term comprising any wireless device or node equipped with aradio interface allowing for at least one of: transmitting signals in ULand receiving and/or measuring signals in DL. A UE herein may comprise aUE (in its general sense) capable of operating or at least performingmeasurements in one or more frequencies, carrier frequencies, componentcarriers or frequency bands. It may be a “UE” operating in single- ormulti-RAT or multi-standard mode.

A cell is associated with a base station, where a base station comprisesin a general sense any node transmitting radio signals in the downlink(DL) and/or receiving radio signals in the uplink (UL). Some examplebase stations are eNodeB, eNB, Node B, macro/micro/pico radio basestation, home eNodeB (also known as femto base station), relay,repeater, sensor, transmitting-only radio nodes or receiving-only radionodes. A base station may operate or at least perform measurements inone or more frequencies, carrier frequencies or frequency bands and maybe capable of carrier aggregation. It may also be a single-radio accesstechnology (RAT), multi-RAT, or multi-standard node, e.g., using thesame or different base band modules for different RATs.

The signaling described is either via direct links or logical links(e.g. via higher layer protocols and/or via one or more network nodes).For example, signaling from a coordinating node may pass another networknode, e.g., a radio node.

The example embodiments are described in the non-limiting examplecontext of an E-UTRAN type system. However, the technology is notlimited thereto, and may apply to any Radio Access Network (RAN),single-RAT or multi-RAT.

In one non-limiting embodiment, a UE may transmit an IDC indicationmessage to the network, e.g., a base station, after a time parameter,e.g., a TDM parameter, or a frequency parameter, e.g., an FDM parameter,changes. In this way, the UE avoids IDC indication signaling insituations where the UE would simply send the same or a slightlymodified IDC indication which would not require responsive action fromthe network. On the other hand, when IDC information changes, it isimportant for the network to receive this information as soon aspractical.

If FDM parameters, e.g., carrier frequencies suffering from IDCinterference, are not expected to change frequently, the UE likely doesnot need to send another IDC indication soon after it sent the previousIDC indication. Some non-optimized UE implementations may changeboundary frequencies suffering from the interference continuously tobypass the IDC indication prohibit timer, but this creates anundesirable and typically unnecessary signaling load. Thus, in oneexample embodiment, the UE may resend the IDC indication irrespective ofthe IDC indication prohibit timer if one or more time base parameters,e.g., TDM parameters, have changed but not when FDM parameters havechanged. Here, it is assumed that the UE does not unnecessarily changethe time-based parameters.

In some other scenarios, frequency-based parameters may be expected tochange relatively often whereas time-based parameters do not. This canoccur for example when an interfering radio uses adaptive frequencyhopping or frequently changes its frequency. In such a case, time-basedparameters are likely to remain substantially the same over a longerperiod. Accordingly, the UE may resend the IDC indication to the networkirrespective of the IDC indication prohibit timer if frequency-based,e.g., FDM, parameters have changed but not when time-based, e.g., TDM,parameters have changed.

The network may configure in which scenario the UE is allowed to send anupdated IDC indication message, e.g., only in the case when TDMparameters have changed or only when FDM parameters have changed.Furthermore, if the UE changes parameters too often, then the networkcan release or override the IDC configuration to control the IDCindication signaling load.

Another non-limiting example embodiment sends an IDC indication afterhandover (HO), i.e., the UE sends an IDC indication after handover (HO).It may be assumed for this example that the UE is not allowed to send anIDC indication having a same content as the previous one irrespective ofthe prohibit timer. Or said differently, for this example it may beassumed that UEs, in the prior art, are generally not allowed to send anIDC indication having a same content as the previous one irrespective ofthe prohibit timer. However, it should also be appreciated that theembodiments described hereinbelow do not necessarily involve the use ofa prohibit timer. In other words, these embodiments can be reduced topractice also without the use of a prohibit timer.

When the UE performs handover to a new eNB, it is desirable for the IDCassistance information to be transferred from the source eNB to thetarget eB over the X2 interface. But this is not always possible.

Consider, for example, a scenario where the UE first sends a measurementreport to the network. Based on the measurement report, the source eNBstarts handover preparation with the target eNB. During thispreparation, parameters related to the UE context are transferred fromthe source node to the target node, which can take some time. After thetarget eNB has confirmed handover, the source eNB sends a handovercommand to the UE. During the time between the measurement report andthe handover command, the UE may send (see e.g. step 303 in FIG. 3) anIDC indication to the source eNB. However, because handover preparation(see e.g. step 302 in FIG. 3) started already, parameters in the justsent IDC indication are not necessarily transferred to the target eNB.

In one example embodiment, which is also schematically illustrated inFIG. 2, this problem is solved by allowing the UE to send 201 the IDCindication with the same content as in the previous IDC indicationmessage if it has performed HO to another cell.

In another example embodiment, which is illustrated in FIG. 3, the UEsends 305 an IDC indication with the same content as in the previousmessage in the target cell if it has sent 303 the IDC indication to thesource eNB later than the previous measurement report has been sent 301.

In a variation of previous example embodiments, the UE may send 305 anIDC indication with the same content as in the previous IDC indicationmessage in the target cell if the UE has sent 303 the IDC indication tothe source eNB a maximum of X seconds before it has received 304 thehandover command. Time X can be a fixed time or a configurable time,e.g., by the network. The time X may for example be 1 second.Alternatively, the time X may take other values such as 0.5, 075, 1.25,1.5 or 2 seconds.

As will be appreciated, IDC indication messages may be transferred tothe network when appropriate and needed but at the same time efficientlyso that unnecessary signaling is avoided thereby saving radio resourcesand processing resources. Also, the embodiments shown in FIGS. 2 and 3,respectively, may allow for ensuring that a target eNB receives correctIDC information. If the UE would not resend the IDC indication messageas proposed, there would be a potential risk that the target eNB hasincorrect information, because as described earlier handover preparationstarted already and parameters in a previously sent IDC indication maynot necessarily have been transferred from the source eNB to the targeteNB. In such scenario, the UE would thus risk continuing to experienceIDC interference, since the target eNB has the incorrect information.

A function block diagram is provided in FIG. 4 which shows a basestation, e.g., an eNB, that can be used in example embodiments describedabove. The base station comprises one or more data processors 12 thatcontrol the operation of the base station. The one or more dataprocessors 12 are connected to radio circuitry 20 that includes multipleradio transceivers 22 with associated antenna(s) 24 a . . . 24 n whichare used to transmit signals to, and receive signals from, other radionodes such as user equipments (UEs). The base station also comprises oneor more memories 14 connected to the one or more data processors 12 andthat store program 16 and other information and data 18 required for theoperation of the base station and to implement the functions describedabove. The base station also includes components and/or circuitry 26 forallowing the base station to exchange information with other basestations and/or other network nodes.

A function block diagram is provided in FIG. 5 which shows a UE 30 thatcan be used in example embodiments described above. The UE 30 comprisesa controller 31 with one or more data processors 32 that control theoperation of the UE 30. The one or more data processors 32 are connectedto multiple radio transceivers 40A, 40B, 40C, . . . , 40N that may beselectively coupled with one or more antenna(s) 44 a . . . 44 n whichare used to transmit signals to, and receive signals from, other radionodes such as base stations. The UE controller 31 also comprises one ormore memories 34 connected to the one or more data processors 32 andthat store program 36 and other information and data 38 required for theoperation of the UE 30 and to implement the UE functions describedabove. The UE 30 also includes IDC interference indication prohibittimer(s) 48 used by the controller 31 along with other factors todetermine when an IDC indication message may be transmitted. One or moreuser interfaces 46 is further provided to allow a user to retrieve,receive, store, and send information.

More particularly, the user equipment UE 30 comprises a controller 31with one or more data processors 32 and one or more memories 34connected to the one or more data processors 32; wherein the one or morememories 34 store program 36 and other information and data 38 which,when, run in the one or more data processors 32 causes the UE 30 to sendan IDC indication message with a same content as in a previously sentIDC indication message if the UE has performed a handover to anothercell. The one or more memories 34 may store program 36 and otherinformation and data 38 which, when, run in the one or more dataprocessors 32 causes the UE 30 to send the IDC indication message withthe same content as in the previously sent IDC indication message in atarget cell if the UE has sent the IDC indication message to a sourceevolved NodeB (eNB) later than a previous measurement report has beensent. Furthermore, the one or more memories 34 may store program 36 andother information and data 38 which, when, run in the one or more dataprocessors 32 causes the UE 30 to send the IDC indication message with asame comment as in the previously sent IDC indication message in atarget cell if the UE has sent the IDC indication message to a sourceeNB a maximum number of seconds before the UE has received a handovercommand. Again, the maximum number of seconds may be a fixed time.Alternatively, the maximum number of seconds may be a configurable time.The time may, for example, be 0.5, 075, 1, 1.25, 1.5 or 2 seconds.

Yet further, the one or more memories 34 may store program 36 and otherinformation and data 38 which, when, run in the one or more dataprocessors 32 causes the UE 30 to transmit an IDC indication message toa network (e.g. a base station) after a time parameter (e.g. a TDMparameter) or a frequency parameter (e.g. a FDM parameter) changes.

Furthermore, the one or more memories 34 may store program 36 and otherinformation and data 38 which, when, run in the one or more dataprocessors 32 causes the UE 30 to resend the IDC indication messageirrespective of an IDC indication prohibit timer 48. For example, theone or more memories 34 may store program 36 and other information anddata 38 which, when, run in the one or more data processors 32 causesthe UE 30 to resend the IDC indication message irrespective of an IDCindication prohibit timer if one or more time parameters (e.g. TDMparameters) have changed but not when frequency parameters (e.g. FDMparameters) have changed. Alternatively, the one or more memories 34 maystore program 36 and other information and data 38 which, when, run inthe one or more data processors 32 causes the UE 30 to resend the IDCindication message irrespective of an IDC indication prohibit timer ifone or more frequency parameters (e.g. FDM parameters) have changed butnot when time parameters (e.g. TDM parameters) have changed.

The technology described throughout this disclosure includes manyadvantages. For example, IDC indication messages may be transferred tothe network when appropriate and needed but at the same time efficientlyso that unnecessary signaling is avoided thereby saving radio resourcesand processing resources. Some of the embodiments may also allow forensuring that a target eNB receives correct IDC information.

Although the description above contains many specifics, they should notbe construed as limiting but as merely providing illustrations of somepresently preferred embodiments. Embodiments described herein may beconsidered as independent embodiments or may be considered in anycombination with each other to describe non-limiting examples. Althoughnon-limiting, example embodiments of the technology were described in aEUTRAN context, the principles of the technology described may also beapplied to other radio access technologies, such as e.g. UTRAN. Indeed,the technology fully encompasses other embodiments which may becomeapparent to those skilled in the art. Reference to an element in thesingular is not intended to mean “one and only one” unless explicitly sostated, but rather “one or more.” All structural and functionalequivalents to the elements of the above-described embodiments that areknown to those of ordinary skill in the art are expressly incorporatedherein by reference and are intended to be encompassed hereby. Moreover,it is not necessary for a device or method to address each and everyproblem sought to be solved by the described technology for it to beencompassed hereby.

The invention claimed is:
 1. A method performed by a user equipment(UE), the method comprising: sending a measurement report to a sourcebase station; sending a first In-Device Coexistence (IDC) indicationmessage to the source base station; performing a handover to a targetcell; determining whether the first IDC message was sent to the sourcebase station after the measurement report; and upon determining thefirst IDC message was sent to the source base station after themeasurement report, sending a second IDC indication message to a targetbase station in the target cell, the second IDC indication messageincluding the same content as the first IDC indication message.
 2. Themethod according to claim 1, wherein the target base station comprises aeNB.
 3. A method performed by a user equipment (UE), the methodcomprising: sending a first In-Device Coexistence (IDC) indicationmessage to a source base station; receiving a handover command;performing a handover to a target cell; determine the UE received thehandover command a maximum number of seconds after sending the first IDCindication message; and sending a second IDC indication message to atarget base station in the target cell, the second IDC indicationmessage including the same content as the first IDC indication message.4. The method according to claim 3, wherein the maximum number ofseconds is a fixed time.
 5. The method according to claim 3, wherein themaximum number of seconds is a configurable time.
 6. A user equipment(UE) comprising a controller with one or more data processors and one ormore memories connected to the one or more data processors; wherein theone or more memories store program information and data which, when runin the one or more data processors causes the UE to: send a measurementreport to a source base station; send a first In-Device Coexistence(IDC) indication message to the source base station; perform a handoverto a target cell; determine whether the first IDC message was sent tothe source base station after the measurement report; and upondetermining the first IDC message was sent to the source base stationafter the measurement report, send a second IDC indication message to atarget base station in the target cell, the second IDC indicationmessage including substantially the same content as the first IDCindication message.
 7. The UE according to claim 6, wherein the targetbase station comprises a eNB.
 8. A user equipment (UE) comprising acontroller with one or more data processors and one or more memoriesconnected to the one or more data processors; wherein the one or morememories store program information and data which, when run in the oneor more data processors causes the UE to: send a first In-DeviceCoexistence (IDC) indication message to a source base station; receive ahandover command; perform a handover to a target cell; determine the UEreceived the handover command a maximum number of seconds after sendingthe first IDC indication message; and send a second IDC indicationmessage to a target base station in the target cell, the second IDCindication message including the same content as the first IDCindication message.
 9. The UE according to claim 8, wherein the maximumnumber of seconds is a fixed time.
 10. The UE according to claim 8,wherein the maximum number of seconds is a configurable time.